KR20170012190A - Oxide sintered body, method for manufacturing same, and oxide film - Google Patents

Abstract

An oxide sintered body excellent in manufacturing stability, film forming stability, discharge stability and mechanical strength, a method for producing the same, and an oxide film having an intermediate refractive index obtained using the oxide sintered body. An oxide sintered body containing In and Si and having a Si content of 0.65 or more and 1.75 or less in Si / In atomic ratio, a relative density of 90% or more, and a bending strength of 90 N / mm 2 or more is produced. An oxide film having a refractive index of 1.70 or more and 1.90 or less is prepared by a sputtering method.

Description

OXIDE SINTERED BODY, METHOD FOR MANUFACTURING SAME, AND OXIDE FILM,

The present invention relates to an oxide sintered body mainly composed of an oxide containing indium and silicon, a method for producing the same, and an oxide film obtained using the oxide sintered body. The present application is also based on Japanese Patent Application No. 2014-113139 filed on May 30, 2014, the entirety of which is incorporated herein by reference.

The oxide film is used in various fields such as a solar battery, a liquid crystal display element, electrodes of various other light receiving elements, or a transparent heat generating element for preventing fogging such as a heat ray reflective film for an automobile or a building, an antistatic film, and a freezing showcase. It is also applied as an optical film represented by an antireflection film, a reflection increasing film, an interference film, a polarizing film and the like. As an optical film, an application as a laminate in which an oxide film having various characteristics is combined has been made.

The spectroscopic characteristics of the oxide multilayer film are determined by the refractive index "n" of each layer and the film thickness "d" when the attenuation coefficient k can be regarded as almost zero. Therefore, in the optical design of the laminate using the oxide film, it is general to perform the calculation based on the data of "n" and "d" of each layer constituting the oxide multi-layer film. In this case, in addition to the combination of the high-refractive-index film and the low-refractive-index film, a multilayer film having more excellent optical characteristics can be obtained by further adding a film (intermediate refractive-index film) having these intermediate refractive indices.

Typical Examples of the high refractive index layer _{(n> 1.90), TiO 2} (n = 2.4), CeO 2 (n = 2.3), ZrO 2 (n = 2.2), Nb 2 O 5 (n = 2.1), Ta 2 O 5 ( n = 2.1), and WO ₃ (n = 2.0). SiO ₂ (n = 1.4), MgF ₂ (n = 1.4) and the like are known as a low refractive index film (n <1.60). Al ₂ O ₃ (n = 1.6), MgO (n = 1.7), Y ₂ O ₃ (n = 1.8) and the like are known as intermediate refractive index films (n = 1.60 to 1.90).

As a method for forming such an oxide film, a sputtering method, a vapor deposition method, an ion plating method, and a solution coating method are generally used. Among them, the sputtering method is an effective method when film formation of a material having a low vapor pressure or control of a precise film thickness is required, and it is widely used industrially since it is very easy to operate.

In the specific sputtering method, a target is used as a raw material for various oxide films. This method generates an argon plasma by causing a glow discharge between an anode and a cathode, with a substrate as an anode and a target as a cathode under a gas pressure of generally about 10 Pa or less. Then, the film is formed by causing the argon cations in the plasma to collide with the target of the negative electrode, thereby depositing the particles of the target component repelled by the deposition onto the substrate.

The sputtering method is classified into a method of generating an argon plasma, and a high-frequency sputtering method using a high-frequency plasma or a direct-current sputtering method using a DC plasma is called a direct-current sputtering method. Generally, the direct current sputtering method is widely used industrially because of the fact that the film forming speed is higher than that of the high frequency sputtering method, the power supply facilities are inexpensive, and the film forming operation can be performed easily. For example, a direct current magnetron sputtering method is widely used also in the production of a transparent conductive thin film.

However, in general, in the sputtering method, when the target of the raw material is an insulating target, it is necessary to use a high-frequency sputtering method, which makes it impossible to obtain a high film forming speed.

On the other hand, the above-mentioned ordinary middle refractive index materials such as Al ₂ O ₃ , MgO, Y ₂ O ₃ and the like are insufficient in conductivity, so that stable discharge can not be realized even when used as a sputtering target. Therefore, in order to obtain the intermediate refractive index film by the sputtering method, it is necessary to perform sputtering (reactive sputtering) while reacting metal particles and oxygen in an atmosphere containing a large amount of oxygen by using a metal target having conductivity.

However, in the reactive sputtering method including a large amount of oxygen, the productivity is remarkably impaired because the deposition rate is very slow. As a result, there is an industrial problem such as an increase in the unit price of the resulting middle refractive index film.

Here, as a material for obtaining a middle refractive index film, an In-Si-O-based oxide sintered body has been proposed (for example, see Patent Document 1). In general, an In-Si-O-based sintered body containing a high concentration of Si has insufficient sinterability. For this reason, in the technique described in Patent Document 1, in order to solve such a problem, a sintered body is obtained by using indium oxide powder and Si powder as raw materials and hot pressing method.

Patent Document 1: Japanese Patent No. 4915065 Patent Document 2: Japanese Patent No. 4424889 Patent Document 3: Japanese Patent Application Laid-Open No. 2007-176706 Patent Document 4: Japanese Patent No. 4028269

However, in the method described in Patent Document 1, although a high-density sintered body having a relative density of 90% or more is obtained according to the conditions, since a Si powder as a non-oxide is used as a raw material, a metal Si phase remains in the sintered body as a result . Therefore, when the film is formed by sputtering using this sintered body as a target, the oxidation reaction of Si occurs at the target surface due to the oxygen contained in the chamber, and very high oxidation heat is generated, so that the surface condition of the target becomes remarkably coarse, The film formation may not be able to continue.

As a method of obtaining another sintered In-Si-O-based oxide having high conductivity, an indium oxide-based low resistance target containing Si and Sn has been proposed (for example, see Patent Document 2). However, since the composition of this target is as small as 0.26 or less in terms of the Si / In atomic ratio, the intermediate refractive index composition is hard to be obtained.

Further, in Patent Document 3, an indium oxide-based low resistance target containing Si and Sn is proposed. However, this target also has a smaller Si content than the target described in Patent Document 2. [ Therefore, problems such as high density and high strength of the oxide-sintered body required for a target containing Si of high concentration remain as it is, and cracks and seizure are generated during production, and it is difficult to realize stable discharge in sputtering .

With respect to a sintered body containing a high concentration of Si, Patent Document 4 proposes a composition to which SnO ₂ and TiO ₂ are added. This method is specialized for reducing the resistance of the In ₂ O ₃ sintered body. When the concentration of SiO ₂ is 7 wt% or more and 40 wt% or less, SnO _{2 is added} to SnO ₂ / (In ₂ O ₃ + SnO ₂ ) = 0.10. &Lt; / RTI &gt; However, when the amount of TiO ₂ having a refractive index of 2.0 or more in addition to the amount of SnO ₂ is large, the refractive index becomes high and a middle refractive index film useful as an oxide film can not be obtained.

As described above, there is a high-density and high-strength sputtering target capable of suppressing cracking and seizure at the time of manufacture and realizing a stable film by sputtering in an indium oxide-based material containing Si at a high concentration I never do that.

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a sintered product of In-Si-O oxide, which is obtained without cracking or seizure, And an object of the present invention is to provide an excellent oxide sintered body, a method for producing the same, and an oxide film having an intermediate refractive index obtained by using the oxide sintered body.

In order to achieve the above object, the oxide-sintered body according to the present invention comprises In and Si, wherein the content of Si is 0.65 or more and 1.75 or less in terms of Si / In atomic ratio, And a relative density calculated from an actual density of the oxide-sintered body with respect to the density calculated from the density of 90% or more and a bending strength of 90 N / mm 2 or more.

In the oxide-sintered body according to the present invention, it is preferable that the proportion of the crystalline phase of the silicate indium compound having a toite bitite structure is 30 mass% or less.

Further, the oxide-sintered body according to the present invention preferably does not contain a metallic Si phase. In the oxide-sintered body according to the present invention, it is preferable that the metal Si phase is not detected by the X-ray diffraction method of the powder of the oxide-sintered body and / or the electron ray diffraction method of the thin piece of the oxide-

Further, it is preferable that the oxide-sintered body according to the present invention does not contain a crystalline silicon dioxide compound phase. In the oxide-sintered body according to the present invention, it is preferable that the crystalline silicon dioxide phase is not detected by the X-ray diffraction method of the powder of the oxide-sintered body and / or the electron ray diffraction method of the thin piece of the oxide-

The oxide-sintered body according to the present invention further contains at least one metal element selected from among trivalent or more metal elements other than In and Si, and the content of M in the case where all the components of the metal element are M M / In atomic ratio of 0.001 or more to 0.05 or less.

The method for producing an oxide-sintered body according to the present invention is a method for producing an oxide-sintered body according to the present invention, in which amorphous silicon dioxide powder is used as a raw material of Si, and a formed body containing amorphous silicon dioxide powder is sintered by a normal pressure sintering method .

Further, in the method for producing an oxide-sintered body according to the present invention, it is preferable that the formed body is sintered at 1100 DEG C or higher and 1400 DEG C or lower.

The oxide film according to the present invention is an oxide film obtained by the sputtering method using the oxide-sintered body as a sputtering target, and has a refractive index of 1.70 or more and 1.90 or less.

According to the present invention, since the mechanical strength is excellent, it is possible to manufacture an oxide sintered body capable of suppressing tearing and cracking during production and during film formation, and capable of forming a stable film without causing abnormal discharge by the sputtering method. As a result, the obtained oxide-sintered body can be used as a sputtering target for forming an oxide film.

Further, according to the present invention, an optically useful intermediate refractive index film can be stably formed and provided by sputtering using an oxide-sintered body as a sputtering target.

(Hereinafter referred to as &quot; present embodiment &quot;) to which the present invention is applied will be described in detail in the following order. The present invention is not limited to the following embodiments, but various modifications can be made without departing from the gist of the present invention.

1. Oxide sintered body

2. Manufacturing method of oxide sintered body

3. Oxide film

4. Example

[One. Oxide sintered body]

First, the oxide-sintered body according to the present embodiment will be described.

The oxide sintered body is for obtaining an oxide film having a desired refractive index, and includes indium (In) and silicon (Si).

Here, the &quot; oxide film having a desired refractive index &quot; means a middle refractive index film. The middle refractive index film refers to a film having a refractive index intermediate between a film having a high refractive index (hereinafter referred to as a "high refractive index film") and a film having a low refractive index (hereinafter referred to as a "low refractive index film").

In general, a high refractive index film means a film having a refractive index "n" of more than 1.90 (n> 1.9), a low refractive index film having a refractive index "n" of less than 1.60 (n <1.6), a middle refractive index film having a refractive index " Is 1.60 or more and 1.90 or less (n = 1.60 to 1.90).

The oxide sintered body is for obtaining a middle refractive index film, but the middle refractive index film referred to herein refers to an oxide film having a refractive index of 1.70 or more and 1.90 or less.

It can be seen that the refractive index of the oxide film depends on the composition of the oxide-sintered body in forming an oxide film having a refractive index of 1.70 or more and 1.90 or less by using this oxide-sintered body as a sputtering target.

Therefore, in the oxide-sintered body, silicon dioxide (SiO ₂ ) is added with indium oxide as the main component, and the content of Si is 0.65 or more and 1.75 or less in terms of Si / In atomic ratio. By including Si in the oxide-sintered body in this way, breakage of the oxide-sintered body can be prevented.

When the Si / In atomic ratio is less than 0.65, the oxide film obtained using the oxide-sintered body has a high refractive index. On the other hand, when the Si / In atomic ratio exceeds 1.75, the refractive index of the oxide film is lowered. Or less of the intermediate refractive index. Therefore, in order to obtain an oxide film having a refractive index of 1.70 or more and 1.90 or less in the oxide-sintered body, the Si content is set to 0.65 or more and 1.75 or less in terms of the Si / In atomic ratio.

In the oxide-sintered body, if the Si content exceeds about 0.6 moles per mole of the In content, the sintering property of the oxide-sintered body is remarkably lowered. Therefore, when crystalline silicon dioxide is used as the starting material of the oxide-sintered body in particular, sintering at ordinary atmospheric pressure becomes very difficult because of low sinterability.

Therefore, in the oxide-sintered body, by using the amorphous silicon dioxide powder as a raw material of Si, an oxide sintered body having a relative density of 90% or more and having more excellent mechanical strength (bending strength) can be obtained.

In calculating the relative density of the oxide-sintered body, since the true density differs greatly depending on the compound present in the oxide-sintered body, definition of true density becomes important. That is, in the oxide-sintered body, the relative density with respect to the density calculated from the existence ratio and the true density of each compound phase constituting the sintered body must be calculated.

For example, in the case where indium oxide (density: 7.18 g / cm3) and amorphous silicon dioxide (density: 2.2 g / cm3) are present singly in the indium oxide-based sintered body containing silicon dioxide in a proportion of 30 mass% The true density is calculated to be 4.28 g / cm &lt; 3 &gt;. However, when the indium silicate compound phase is formed in the indium oxide-based sintered body, since the true density is calculated to be 5.05 g / cm 3, if the true density with the existence ratio of the indium silicate compound is not adopted, There is a car. For this reason, in the oxide-sintered body, the relative density with respect to the density calculated from the existence ratio and the true density of each compound phase is employed.

That is, the relative density referred to here is a density of the oxide-sintered body with respect to the density (A) calculated by adding the ratio of each compound phase to the true density of the indium oxide phase, the silicon dioxide phase, and the indium silicate contained in each oxide phase contained in the oxide- (B / A) x 100 [%], which is the ratio (percentage) of the measured value B of the measured value (B). The density of the oxide-sintered body can be measured by, for example, the Archimedes method.

The relative density of the oxide-sintered body greatly affects the discharge stability of the oxide-sintered body in sputtering as well as securing a high yield at the time of production. Here, by setting the relative density to 90% or more, particles (fine particles) and nodules (protrusions) generated at the time of sputtering discharge can be reduced, and arcing (abnormal discharge) have. As described above, since the oxide-sintered body can stabilize the sputter discharge, it is possible to improve the quality and uniformity of the obtained oxide film.

It should be noted that, in forming the oxide film by using the oxide-sintered body as a sputtering target, the stabilization of the discharge in the sputtering is dependent not only on the density of the oxide-sintered body but also on the compound phase constituting the oxide-sintered body.

The oxide-sintered body contains a crystal phase of a silicate indium compound having a Thortveitite structure in a proportion of 30 mass% or less, and when the content of the crystal phase exceeds 30 mass% .

Herein, the silicate indium of the tort-butite type structure is a compound described in JCPDS card (31-600) and Journal of Solid State Chemistry 2, 199-202 (1970). In the oxide-sintered body, even if the composition is slightly different from the stoichiometric composition, or a part of the indium silicic acid compound is substituted with another ion, the oxide-sintered body may be one that retains the crystal structure.

In the oxide-sintered body, there is no precipitated phase of Si (hereinafter simply referred to as &quot; Si phase &quot;) and / or a silicon dioxide compound phase. That is, in the oxide-sintered body, for example, the oxide-sintered body obtained by pulverization is subjected to the generation phase measurement by X-ray diffraction using CuK? Ray or the thin oxide-sintered body obtained by processing with a focused ion beam (FIB: Focused Ion Beam) Si phase (metal Si phase) and / or silicon dioxide compound phase can not be detected due to generation phase measurement by electron beam ore.

When the oxide-sintered body is used as a sputtering target by making the oxide-sintered body free from the Si phase, sputtering can be performed without causing significant roughness of the target surface which can not be achieved by the conventional method. For this reason, it can be explained as follows.

The mechanism of film formation in general sputtering is that argon ions in the plasma impinge on the target surface and repel particles of the target component to deposit on the substrate.

When the oxide-sintered body in which the Si phase is present is formed as a sputtering target, oxygen supplied when oxygen or oxygen-containing argon gas is introduced into the oxide-sintered body and Si in the oxide-sintered body are oxidized by plasma heating do. In this oxidation reaction, a very high heat of combustion of the oxidation occurs at 930 kJ / mol, and it can be seen that the local surface heat causes remarkable roughness of the target surface.

Particularly, when the crystalline silicon dioxide compound phase which is ovoid is present in the oxide sintered body, even when the density of the oxide sintered body is remarkably low, anomalous discharge is frequent, resulting in remarkable roughness of the target surface.

On the other hand, in the case where the oxide sintered body, which does not contain the Si phase and / or the crystalline silicon dioxide compound phase and is densified with a relative density of 90% or more, is used as a target, abnormal phenomena such as remarkable roughness of the target surface and arcing So that stable discharge can be achieved.

The oxide sintered body has a bending strength of 90 N / mm 2 or more. The oxide-sintered body having such a bending strength can prevent cracking of the target or cracking and sputtering during discharge in sputtering at the time of production.

When the bending strength is less than 90 N / mm 2, cracks of the target occur at the time of production, which causes deterioration of the yield. Further, even when discharging in the sputtering, cracking and tearing are likely to occur.

The bending strength of the oxide-sintered body is basically measured by performing a three-point bending test according to the method according to JIS R1601. That is, an oxide sintered body having a length of 40 mm, a width of 4 mm and a thickness of 3 mm was processed into a sample piece, and a metal jig was pressed thereon at a speed of 0.5 mm / minute, The load is measured to calculate the bending strength. Then, two oxide-sintered bodies produced under the same conditions are provided for the strength test, and the average value is regarded as the bending strength.

In the oxide-sintered body, at least one metal element selected from a trivalent or higher-valent metal element may be contained as a metal element (third component) other than In and Si. By adding the metal element, the density and the mechanical strength of the oxide-sintered body can be improved. However, in the case of a single-valence divalent metal element, there is a fear that the oxide sintered body becomes highly resistive. Therefore, in the oxide-sintered body, a metal element having three or more valences other than In and Sn is used. Examples of such a metal element include Ti (titanium), Sn (tin), Y (yttrium), Ga (gallium), Ta (tantalum), and Al (aluminum).

The content of the trivalent or higher-valent metal element other than In and Si is set to be 0.001 or more and 0.05 or less in terms of M / In atomic ratio, when the total components of metal elements other than In and Si are M. If the M / In atomic ratio is less than 0.001, the effect of reducing the resistance can not be sufficiently obtained. On the other hand, if the M / In atomic ratio exceeds 0.05, the refractive index may increase. Therefore, the content of the trivalent or more metal element other than In and Si is preferably 0.001 or more and 0.05 or less in terms of M / In atomic ratio.

As described above, the oxide-sintered body is characterized in that it contains In and Si, the Si content is 0.65 or more and 1.75 or less in Si / In atomic ratio, the relative density is 90% or more, and the bending strength is 90 N / will be.

The sputtering target for producing an oxide film using such an oxide sintered body has excellent mechanical strength because of a relative density of 90% or more and a bending strength of 90 N / mm 2 or more, and cracks and seizure In addition to reducing particles and nodules, abnormal phenomena such as remarkable roughness and arcing on the target surface can be avoided, and stable discharge can be continued.

When the sputtering using the sputtering target for oxide film production is used, the content of Si in the oxide-sintered body is 0.65 or more and 1.75 or less in terms of Si / In atomic ratio, so that an oxide film having a refractive index of 1.70 or more and 1.90 or less is stably obtained by sputtering .

[2. Manufacturing method of oxide-sintered body]

Next, a method of manufacturing the oxide-sintered body according to the present embodiment will be described.

A method for producing an oxide sintered body includes a first step of obtaining a granulated powder by combining raw powder of components constituting the oxide sintered body at a predetermined ratio, a second step of molding the obtained granulated powder to obtain a molded body, Thereby obtaining a sintered body.

<2-1. First Process (Assembly Process) >

The first step is a granulation step of obtaining granules by combining the raw material powders of the components constituting the oxide sintered body at a predetermined ratio, mixing them with water or various additives to obtain a slurry, and drying and assembling the obtained slurry.

In the first step, indium oxide powder is used as a raw material of In, and silicon dioxide powder is used as a raw material of Si. In particular, amorphous silicon dioxide powder is used as raw material powder.

Here, when a crystalline silicon dioxide powder such as quartz is used as a raw material for Si, the sintering property is low, and it is necessary to increase the firing temperature to a temperature exceeding 1400 캜. However, if the firing temperature exceeds 1400 占 폚, indium silicate crystals of a tritiated phase structure (single crystal), which is an intermediate compound phase, are produced at a ratio exceeding 30% by mass, resulting in a decrease in strength from a change in crystal structure .

Therefore, when amorphous silicon dioxide powder is used as a raw material of Si, even when the temperature is lower than 1400 DEG C, which is capable of inhibiting the formation of a silicate indium crystal having a toite bitite structure, the silicate indium compound It is possible to obtain an oxide sintered body having almost no voids without generating an image.

In the first step, an amorphous silicon dioxide powder is used instead of the non-oxide Si powder (metal Si powder) as a raw material of Si. Thereby, an oxide sintered body can be stably produced, and an oxide sintered body in which an Si phase and / or a silicon dioxide compound phase is not present can be produced.

On the other hand, when Si powder is used as the raw material, there is a risk that sintering due to local heat generation due to oxidation of Si occurs in atmospheric pressure sintering in an atmospheric or oxygen atmosphere, and it becomes very difficult to manufacture a stable sintered body. Further, even if the oxide-sintered body is obtained, the Si phase and / or the silicon dioxide compound phase remain, and there is a possibility that remarkable roughness of the target surface occurs during the sputtering film formation. Therefore, in the first step, amorphous silicon dioxide powder is used as a raw material of Si.

In the first step, if necessary, an oxide powder containing a trivalent or more metal element other than In and Si may be added. Examples of such oxide powders include titanium dioxide (TiO ₂ ), tin dioxide (SnO ₂ ), yttrium oxide (Y ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), tantalum oxide (V) (Ta ₂ O ₅ ), and aluminum oxide (Al ₂ O ₃ ).

The median diameter of each raw material powder is not particularly limited, but if the particle diameter is too large, the relative density of the oxide-sintered body is lowered, and the mechanical strength and conductivity of the sintered body are lowered.

In the first step, the raw material powders are weighed and weighed at a ratio that Si is 0.65 or more and 1.75 or less in terms of Si / In atomic ratio, as described above. When oxide powder of a trivalent or higher metal element other than In and Si is further added to the oxide powder, all the components of the oxide powder to be added are made to be M and weighed so as to have a content of M / In atomic ratio of 0.001 to 0.05 do.

Next, in the first step, each raw material powder in which a predetermined amount is weighed is mixed with an organic binder such as pure water, polyvinyl alcohol, or an acrylic binder, a dispersant such as an ammonia neutralized product of an acrylic acid methacrylic acid copolymer or an acrylic acid- And mixed so that the concentration of the raw material powder is 50% by mass or more and 80% by mass or less, preferably 65% by mass, to obtain a slurry. Then, wet milling is performed so that the mixed powder in the slurry has a predetermined median diameter.

The median diameter of the powder obtained by the wet pulverization is not particularly limited, but it is preferable to pulverize until the powder becomes 1 탆 or less. If the median diameter exceeds 1 占 퐉, not only the relative density of the sintered body is lowered but also the contact area between the particles is lowered so that the densification of the oxide sintered body is inhibited and consequently the density, mechanical strength and conductivity There is a possibility that the oxide-sintered body having the oxide-sintered body can not be obtained.

In the wet grinding, it is preferable to use a grinding apparatus such as a bead mill into which a hard ball (zirconium dioxide (ZrO ₂ ) balls or the like) having a particle diameter of 2.0 mm or less is charged. As a result, aggregation of each raw material powder can be reliably removed.

On the other hand, in the case of using a grinding apparatus such as a ball mill into which balls having a particle diameter exceeding 2.0 mm are used, it is difficult to crush particles up to a particle diameter of 1.0 탆 or less. As a result, the densification of the oxide- The strength and conductivity become insufficient.

As described above, in the first step, the slurry obtained by mixing the raw powder is subjected to wet pulverization, and then the slurry obtained by stirring for 30 minutes or longer is dried and assembled to obtain granulated powder.

<2-2. Second Step (Molding Step) >

The second step is a molding step for obtaining a molded article by pressure-molding the granular material obtained in the above-mentioned first step.

In the second step, pressure molding is performed at a pressure of, for example, 196 MPa (2.0 ton / cm 2) or more to remove voids between the particles of the granules. The press forming method is not particularly limited, but it is preferable to use a cold isostatic press (CIP) capable of applying a high pressure.

However, since the apparatus for setting the molding pressure to a molding pressure exceeding 300 MPa is very expensive, the production cost is high and it is economically very inefficient.

Therefore, in the second step, the molded article can be manufactured by performing the molding at a molding pressure of preferably at least 196 MPa, more preferably at a molding pressure of not less than 196 MPa and not more than 300 MPa.

<2-3. Third step (firing step) >

The third step is a sintering step of obtaining the oxide-sintered body by sintering the molded body obtained in the second step described above at normal pressure.

The sintering treatment in the third step is preferably performed at a sintering temperature of 1100 DEG C or higher and 1400 DEG C or lower, more preferably 1250 DEG C or higher and 1350 DEG C or lower.

When the sintering temperature is less than 1100 占 폚, the viscous flow of the amorphous silicon dioxide is insufficient, so that the density of the desired oxide sintered body can not be obtained. On the other hand, when the firing temperature exceeds 1400 占 폚, the crystallization of silicon dioxide or the formation of the silicate indium compound, which is a torbbitite structure, proceeds remarkably. As a result, the proportion of the silicate indium compound phase exceeds 30 mass%, and the bending strength is lower than 90 N / mm &lt; 2 &gt;.

In the third step, it is preferable that sintering is performed at a sintering temperature of from 1100 DEG C to 1400 DEG C from the viewpoint of producing a desired oxide sintered body.

In the third step, the amorphous silicon dioxide powder is used as a raw material of Si contained in the formed body, and the sintered property is improved by using the formed body. Then, sintering (normal pressure sintering) at normal atmospheric pressure becomes possible, and a high-density oxide sintered body can be produced.

As described above, the production method of the oxide-sintered body is characterized in that an amorphous silicon dioxide powder as a raw material of Si, and optionally an oxide powder of a metal element of trivalent or more other than In and Si are used, By sintering at the following sintering temperature, the above-described oxide sintered body having characteristics as described above can be obtained without breakage.

In the oxide-sintered body manufacturing method, it is possible to manufacture the oxide-sintered body capable of suppressing seizure and cracking during production and during film formation and capable of forming a stable film without causing abnormal discharge by the sputtering method without breakage.

The obtained oxide sintered body can be formed into a desired target shape by circumferential machining and surface grinding to bond the oxide sintered body after machining to a backing plate. The target shape is preferably a flat plate shape or a cylindrical shape, but is not limited thereto.

The sputtering target formed in this way can stably discharge an oxide film having a refractive index of 1.70 or more and 1.90 or less which is optically useful when the sputtering is carried out by preventing arcing from occurring due to low density and discharging stably.

[3. Oxide film]

Next, the oxide film according to the present embodiment will be described.

The oxide film is formed by depositing an oxide sintered body having the above-described characteristics as a sputtering target on a substrate by a sputtering method.

As described above, the oxide film contains In and Si, the content of Si is 0.65 or more and 1.75 or less in terms of Si / In atomic ratio, and the ratio of the abundance ratio and the true density of each compound phase constituting the oxide- The oxide sintered body having a relative density of 90% or more and a bending strength of 90 N / mm 2 or more calculated from actual measured values of the density of the oxide sintered body as a raw material and reflecting the composition of the oxide sintered body.

In the case where three or more metal elements other than In and Si are further added to the oxide-sintered body, the content of M in the case where all the metal elements to be added are M is 0.001 or more and 0.05 or less in terms of M / In atomic ratio, As a raw material, and is an oxide film reflecting the composition of the oxide-sintered body. Details of the trivalent or more metal elements other than In and Si are as described above, and therefore, the description thereof is omitted here.

Therefore, the oxide film is a middle refractive index film composed of an oxide containing In, Si, and optionally a trivalent or higher metal element other than In and Si, and having a refractive index of 1.70 or more and 1.90 or less.

The thickness of the oxide film is not particularly limited and may be appropriately set in accordance with the film formation time, the kind of the sputtering method, and the like, and is, for example, about 5 nm or more and 300 nm or less.

In the sputtering, the sputtering method is not particularly limited, and a sputtering method such as DC (direct current) sputtering, pulsed DC sputtering, AC (alternating current) sputtering, RF (high frequency) magnetron sputtering, .

As the substrate, for example, glass, resin such as PET (polyethylene terephthalate) or PES (polyethersulfone) can be used.

The film formation temperature of the oxide film by sputtering is not particularly limited, but is preferably set to, for example, 50 캜 or more and 300 캜 or less. If the film-forming temperature is lower than 50 캜, the obtained oxide film may contain moisture by condensation. On the other hand, if the film-forming temperature exceeds 300 캜, the substrate may be deformed or stress may remain in the oxide film to cause cracking.

The pressure in the chamber at the time of sputtering is not particularly limited, but it is preferable to perform vacuum pumping at about 5 x 10 &lt; ^-5 &gt; Pa. When a sputtering target having a diameter of 152.4 mm (6 inches) is used as the power output to be supplied during sputtering, the power output is usually 10 W or more and 1000 W or less, preferably 300 W or more and 600 W or less.

Examples of the carrier gas during the sputtering include a gas such as oxygen (O ₂ ), helium (He), argon (Ar), xenon (Xe), krypton (Kr) desirable. When a mixed gas of argon and oxygen is used, the flow ratio of argon and oxygen is generally set to Ar: O ₂ = 100: 0 to 80: 20, preferably 100: 0 to 90: 10.

As described above, in the oxide film, since the characteristic oxide sintered body as described above is used as a sputtering target for forming an oxide film and the composition of the oxide sintered body is reflected, An intermediate optically useful refractive index film made of an oxide containing at least three metal elements and having a refractive index of 1.70 or more and 1.90 or less.

Further, by using the oxide-sintered body as a sputtering target for forming an oxide film, arcing can be prevented from occurring during sputtering, and an oxide film excellent in discharge stability can be obtained.

Example

[4. [Example]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the following examples and comparative examples of the present invention, but the present invention is not limited to these examples and comparative examples.

(Example 1)

&Lt; Production of oxide sintered body >

In Example 1, the In ₂ O ₃ powder and the amorphous SiO ₂ powder each having a median diameter of 1.0 μm or less were used as raw material powders and were combined in such a ratio that the Si / In atomic ratio was 1.0, and the raw material powder concentration was 65 mass% 40% by mass of pure water, 2% by mass of polyvinyl alcohol as an organic binder and 1.5% by mass of an acrylic acid methacrylic acid copolymer ammonia neutralizing agent as a dispersant were mixed and a slurry was prepared in a mixing tank.

Next, in Example 1, using a bead mill device (LMZ type, manufactured by Asahiwa Fine Technology Co., Ltd.) into which a hard ZrO ₂ ball having a particle diameter of 0.5 mm is inserted, when the median diameter of the raw material powder becomes 0.7 탆 Wet grinding was carried out. In order to measure the median diameter of the raw material powder, a laser diffraction particle size distribution measuring apparatus (SALD-2200 manufactured by Shimadzu Corporation) was used.

Thereafter, in Example 1, the slurry obtained by mixing and stirring the respective raw materials for 30 minutes or more was sprayed and dried with a spray drier (ODL-20 type, manufactured by Okawara Kakou Co., Ltd.) to obtain granulated powder.

Next, in Example 1, the granulated powder was molded by applying a pressure of 294 MPa (3.0 ton / cm2) in a cold isostatic press, and the obtained molded article of about 200 mm in diameter was sintered at an atmospheric pressure baking furnace equipped with a zirconia- , And fired for 20 hours to obtain an oxide-sintered body.

In Example 1, the obtained oxide-sintered body was processed so as to have a diameter of 152.4 mm (6 inches) and a thickness of 5 mm. In addition, although 20 oxide-sintered bodies were produced, no cracks occurred during sintering and processing.

Thereafter, in Example 1, the end member of the obtained oxide-sintered body was pulverized and powder X-ray diffraction measurement using CuK? Ray was carried out. As a result, the In ₂ Si ₂ O ₇ phase and In ₂ O ₃ Phase was detected. However, no peak of the Si phase or the crystal phase on the SiO ₂ compound was detected. The weight ratio of each compound phase was analyzed by Rietveld analysis. The ratio of In ₂ Si ₂ O ₇ phase was 15.2 mass% and the proportion of In ₂ O ₃ phase was 84.8 mass%.

In Example 1, the Si / In atomic ratio contained in the result of quantitative analysis of the oxide-sintered body obtained by ICP (Inductively Coupled Plasma) emission spectroscopic analysis (SPS4000, manufactured by Seiko Instruments Inc.) , Which was 1.0, which is the same as the feed composition.

In Example 1, the ratio of each compound with the amount of amorphous SiO ₂ was calculated from the results of the Rietveld analysis and the quantitative analysis. As a result, the mass ratio of the In ₂ Si ₂ O ₇ phase to the In ₂ O ₃ phase was 11.1% different from 62.0% by weight, an amorphous SiO ₂ compound phase was 26.8% by mass.

Next, in Example 1, the density (B) of the oxide-sintered body was measured by the Archimedes method to find that the density of the In ₂ Si ₂ O ₇ crystal as the tobitite structure was 5.05 g / cm 3, The relative density was calculated with respect to the theoretical density of 4.34 g / cm 3 (A) calculated from the density of In ₂ O ₃ crystals of 7.18 g / cm 3 and the density of amorphous SiO ₂ of 2.2 g / cm 3 and the ratio of each phase, 99.8% (= (B / A) x 100 [%]).

In Example 1, a sample piece was produced from an oxide-sintered body. Then, the sample piece was processed into a rod shape by a method in accordance with JIS R1601, and a three-point bending test was conducted. As a result, the calculated bending strength was 98.6 N / mm 2.

&Lt; Preparation of oxide film &

In Example 1, the oxide-sintered body was processed so as to have a diameter of 152.4 mm (6 inches) and a thickness of 5 mm, and bonded to a backing plate made of oxygen-free copper using metal indium to obtain a sputtering target.

Next, in Embodiment 1, film formation by DC sputtering was performed using a sputtering target. An alkali-free glass substrate (Corning # 7059, thickness t) was deposited on the substrate for film formation while the obtained sputtering target was attached to the cathode for non-magnetic target of a magnetron sputtering apparatus (SBH-2206, : 1.1 mm), the distance between the target and the substrate was fixed at 60 mm.

In Example 1, vacuum evacuation was performed until the pressure became 5 × 10 ^-5 Pa or less, pure Ar gas and pure Ar + O ₂ gas were introduced so that the O ₂ concentration became 0.4%, and the gas pressure was set to 0.6 Pa , And 300 W of direct current power were applied to perform pre-sputtering.

In Example 1, sufficient free sputtering was performed, and then a glass substrate was placed just above the center of the sputtering target (non-etched portion), and an oxide film having a film thickness of 200 nm was formed by sputtering with no heating.

As a result, in Example 1, no crack occurred in the sputtering target, and no remarkable roughness or abnormal discharge of the target surface occurred for 10 minutes from the beginning of the film formation. Further, the refractive index of the obtained oxide film was measured with an ellipsometer to find that it was 1.79.

In Example 1, the production conditions and properties of the oxide-sintered body obtained in Example 1, and the film-forming stability and physical properties of the oxide film are shown in Table 1. The results of Examples 2 to 7 and Comparative Examples 1 to 6, which will be described later, are also shown in Table 1 in the same manner as in Example 1.

(Example 2)

&Lt; Production of oxide sintered body >

In Example 2, an oxide-sintered body was produced in the same manner as in Example 1 except that the Si / In atomic ratio was set to be 0.65, and the density of the oxide-sintered body, the existence ratio of each compound phase, the presence or absence of the Si phase and the bending strength were Respectively. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Example 2, as shown in Table 1, the proportion of In ₂ Si ₂ O ₇ phase was 30 mass% or less, Si phase was not detected, and the desired relative density and bending strength were satisfied. Further, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but the oxide-sintered bodies were free from cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Example 2, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Example 2, as shown in Table 1, cracks were not generated in the sputtering target, and no significant roughness or abnormal discharge of the target surface occurred for 10 minutes from the beginning of the film formation. The refractive index of the obtained oxide film was 1.88.

(Example 3)

&Lt; Production of oxide sintered body >

In Example 3, an oxide-sintered body was fabricated in the same manner as in Example 1 except that the Si / In atomic ratio was 1.75, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence or absence of the Si phase and the bending strength were Respectively. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Example 3, as shown in Table 1, the proportion of In ₂ Si ₂ O ₇ phase was 30 mass% or less, Si phase was not detected, and the desired relative density and bending strength were satisfied. Further, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but the oxide-sintered bodies were free from cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Example 3, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Example 3, as shown in Table 1, cracks were not generated in the sputtering target, and remarkable roughness or abnormal discharge of the target surface did not occur for 10 minutes from the beginning of the film formation. The refractive index of the obtained oxide film was 1.73.

(Example 4)

&Lt; Production of oxide sintered body >

In Example 4, an oxide-sintered body was produced in the same manner as in Example 1 except that the sintering temperature was set to 1150 캜, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence of the Si phase and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Example 4, no Si phase was detected as shown in Table 1, and the desired relative density and bending strength were satisfied. Further, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but the oxide-sintered bodies were free from cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Example 4, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Example 4, as shown in Table 1, cracks were not generated in the sputtering target, and no remarkable roughness or abnormal discharge of the target surface occurred for 10 minutes from the beginning of the film formation. The refractive index of the obtained oxide film was 1.78.

(Example 5)

&Lt; Production of oxide sintered body >

In Example 5, an oxide-sintered body was produced in the same manner as in Example 1 except that the sintering temperature was 1350 DEG C, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence of Si phase and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Example 5, as shown in Table 1, the ratio of In ₂ Si ₂ O ₇ phase was 30 mass% or less, Si phase was not detected, and the desired relative density and bending strength were satisfied. Further, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but the oxide-sintered bodies were free from cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Example 5, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Example 5, as shown in Table 1, cracks were not generated in the sputtering target, and no remarkable roughness or abnormal discharge of the target surface occurred for 10 minutes from the beginning of the film formation. The refractive index of the obtained oxide film was 1.80.

(Example 6)

&Lt; Production of oxide sintered body >

In Example 6, except that TiO ₂ powder having a median diameter of 1.0 탆 or less including Ti in addition to the In ₂ O ₃ powder and the amorphous SiO ₂ powder was used and the Ti / In atomic ratio was 0.03, The oxide-sintered body was produced in the same manner as in Example 1, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence or absence of the Si phase and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Example 6, as shown in Table 1, the proportion of In ₂ Si ₂ O ₇ phase was 30 mass% or less, Si phase was not detected, and the desired relative density and bending strength were satisfied. Further, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but the oxide-sintered bodies were free from cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Example 6, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Example 6, as shown in Table 1, cracks were not generated in the sputtering target, and remarkable roughness or abnormal discharge of the target surface did not occur for 10 minutes from the beginning of the film formation. The refractive index of the obtained oxide film was 1.85.

(Example 7)

&Lt; Production of oxide sintered body >

In Example 7, except that SnO ₂ powder having a median diameter of 1.0 탆 or less including Sn in addition to In ₂ O ₃ powder and amorphous SiO ₂ powder was used and the Sn / In atom ratio was 0.02, The oxide-sintered body was produced in the same manner as in Example 1, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence or absence of the Si phase and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Example 7, as shown in Table 1, the proportion of In ₂ Si ₂ O ₇ phase was 30 mass% or less, Si phase was not detected, and the desired relative density and bending strength were satisfied. Further, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but the oxide-sintered bodies were free from cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Example 7, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Example 7, as shown in Table 1, cracks were not generated in the sputtering target, and no remarkable roughness or abnormal discharge of the target surface occurred for 10 minutes from the beginning of the film formation. The refractive index of the obtained oxide film was 1.81.

(Comparative Example 1)

&Lt; Production of oxide sintered body >

In Comparative Example 1, an oxide-sintered body was produced in the same manner as in Example 1 except that the Si / In atomic ratio was adjusted to be 0.5, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence or absence of the Si phase and the bending strength were Respectively. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Comparative Example 1, the proportion of In ₂ Si ₂ O ₇ phase was 30 mass% or less as shown in Table 1, and Si phase was not included, and the desired relative density and bending strength were satisfied. Though 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, these oxide-sintered bodies were free from cracking during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Comparative Example 1, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Comparative Example 1, as shown in Table 1, cracks were not generated in the sputtering target, and no significant roughness or abnormal discharge of the target surface occurred for 10 minutes from the beginning of the film formation. However, the refractive index of the obtained oxide film was 1.94. In Comparative Example 1, a film having a desired refractive index of 1.70 or more and 1.90 or less could not be obtained.

(Comparative Example 2)

&Lt; Production of oxide sintered body >

In Comparative Example 2, an oxide-sintered body was produced in the same manner as in Example 1 except that the Si / In atomic ratio was 2.0, and the density of the oxide-sintered body, the presence ratio of each compound phase, the Si phase and the bending strength were Respectively. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Comparative Example 2, as shown in Table 1, Si phase was not included and a desired relative density and bending strength were satisfied. Though 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, these oxide-sintered bodies were free from cracking during sintering and processing. However, the ratio of the In ₂ Si ₂ O ₇ phase was 30 mass% or more.

&Lt; Preparation of oxide film &

Subsequently, in Comparative Example 2, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Comparative Example 2, as shown in Table 1, cracks were not generated in the sputtering target, and remarkable roughness or abnormal discharge of the target surface did not occur for 10 minutes from the beginning of the film formation. However, the refractive index of the obtained oxide film was 1.65. In Comparative Example 2, a film having a desired refractive index of 1.70 or more and 1.90 or less could not be obtained.

(Comparative Example 3)

&Lt; Production of oxide sintered body >

In Comparative Example 3, an oxide-sintered body was produced in the same manner as in Example 1 except that the sintering temperature was 1000 캜, and the density of the oxide-sintered body, the existence ratio of each compound phase, the presence of Si and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Comparative Example 3, no In ₂ Si ₂ O ₇ phase and Si phase were detected as shown in Table 1. However, since the relative density was 70.4% and the bending strength was 19.3 N / mm 2, the desired relative density and bending strength were not satisfied. Though 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, 15 pieces of cracks were generated in these oxide-sintered bodies during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Comparative Example 3, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Comparative Example 3, as shown in Table 1, no significant roughness of the target surface occurred for 10 minutes from the beginning of the film formation, and the refractive index of the obtained oxide film was 1.78.

However, in Comparative Example 3, an abnormal discharge occurred at the time of film formation, and a crack occurred in the target after film formation.

(Comparative Example 4)

&Lt; Production of oxide sintered body >

In Comparative Example 4, an oxide-sintered body was produced in the same manner as in Example 1 except that the firing temperature was 1500 캜, and the density of the oxide-sintered body, the presence ratio of each compound phase, the presence of Si phase and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Comparative Example 4, as shown in Table 1, the Si phase was not detected and the relative density was 90% or more. However, the ratio of the In ₂ Si ₂ O ₇ phase was 95.8 mass%, and the desired bending strength was not satisfied. In addition, 20 pieces of oxide-sintered bodies were produced and processed in the same manner as in Example 1, but these oxide-sintered bodies had six cracks during sintering and processing.

&Lt; Preparation of oxide film &

Subsequently, in Comparative Example 4, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Comparative Example 4, no significant roughness of the target surface occurred for 10 minutes from the beginning of the film formation, as shown in Table 1, and the refractive index of the obtained oxide film was 1.77.

In Comparative Example 4, however, an anomalous discharge occurred during film formation and a crack occurred in the target after film formation.

(Comparative Example 5)

&Lt; Production of oxide sintered body >

In Comparative Example 5, an oxide-sintered body was produced in the same manner as in Example 1 except that the crystalline SiO ₂ powder was used as the SiO ₂ raw material, and the density of the oxide-sintered body, the existence ratio of each compound phase, the presence or absence of the Si phase and the bending strength were Respectively. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Comparative Example 5, as shown in Table 1, the Si phase was not detected and the ratio of the In ₂ Si ₂ O ₇ phase was 30 mass% or less. However, the relative density was 76.4% and the bending strength was 45.9 N / mm &lt; 2 &gt;, and a desired value could not be obtained. In addition, 20 oxide-sintered bodies were produced and processed in the same manner as in Example 1, but eight cracks occurred.

&Lt; Preparation of oxide film &

Subsequently, in Comparative Example 5, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Comparative Example 5, no remarkable roughness of the target surface occurred for 10 minutes from the beginning of the film formation, as shown in Table 1, and the refractive index of the obtained oxide film was 1.80.

However, in Comparative Example 5, an anomalous discharge occurred during film formation, and a crack occurred in the target after film formation.

(Comparative Example 6)

&Lt; Production of oxide sintered body >

In Comparative Example 6, an In ₂ O ₃ powder having a median diameter of 1.0 μm or less and a metal Si powder having a median diameter of 5 μm were mixed as a raw material powder in a three-dimensional mixer, and the obtained mixed powder was mixed with a powder The sintered oxide was produced in the same manner as in Example 1 except that the oxide sintered body was hot pressed under the conditions of a sintering temperature of 900 캜 and a pressure of 4.9 MPa to prepare an oxide sintered body and the density of the oxide sintered body, The presence or absence of the Si phase and the bending strength were measured. The relative density was calculated from the density of the oxide-sintered body and the ratio of each compound phase.

As a result, in Comparative Example 6, the relative density of the obtained oxide-sintered body was 90% or more, but the proportion of In ₂ Si ₂ O ₇ phase exceeded 30% by mass and the Si phase was detected and the bending strength was 90 N / mm &lt; 2 &gt; In addition, 20 oxide-sintered bodies were produced and processed in the same manner as in Example 1, but five cracks occurred.

&Lt; Preparation of oxide film &

Subsequently, in Comparative Example 6, in the same manner as in Example 1, the oxide-sintered body was bonded to a backing plate made of oxygen-oxygen copper using metal In to prepare a sputtering target. Then, an oxide film was formed using the sputtering target.

As a result, in Comparative Example 6, as shown in Table 1, since the remarkable roughness and anomalous discharge of the target surface were frequent immediately after the start of film formation, the film formation was stopped, and as a result, a crack occurred in the target after film formation. As described above, in the oxide-sintered body obtained in Comparative Example 6, stable discharge was difficult at the time of film formation.

Thus, in Examples 1 to 5, as shown in Table 1, amorphous SiO ₂ powder was used as a raw material of Si, and In and Si were contained, and the content of Si was 0.65 Or more and 1.75 or less, respectively, to obtain a granulated powder. The granulated powder obtained by pressure-molding the granulated powder is sintered at a sintering temperature of 1100 DEG C or more and 1400 DEG C or less by a normal pressure sintering method, Each oxide sintered body was obtained.

As a result, it was confirmed that the oxide-sintered bodies obtained by Examples 1 to 5 were useful as a sputtering target for stably obtaining a middle refractive index film having a refractive index of 1.70 or more and 1.90 or less.

In Examples 6 and 7, amorphous SiO ₂ powder was added as shown in Table 1, and TiO ₂ and SnO ₂ were used as an oxide powder containing at least trivalent metal elements other than In and Si And each of the raw material powders is weighed and combined in such a ratio that the content of Ti and Sn is 0.001 or more and 0.05 or less in terms of the ratio of Ti / In and Sn / In atomic ratio to obtain a granulated powder, By sintering at a sintering temperature of 1200 ° C or higher and 1400 ° C or lower, each oxide sintered body was obtained without breakage.

As a result, it was confirmed that each of the oxide-sintered bodies obtained in Example 6 and Example 7 was useful as a sputtering target for stably obtaining a middle refractive index film having a refractive index of 1.70 or more and 1.90 or less.

On the other hand, in Comparative Examples 1 to 6, as shown in Table 1, in comparison with the production method of the oxide-sintered body obtained in Example 1, the Si / In atom ratio, the sintering temperature, the Si raw material, Was produced by a production method different from that of Example 1 to obtain respective oxide-sintered bodies.

As a result, the oxide-sintered bodies obtained in Comparative Examples 1 to 6 could not stably obtain a middle refractive index film having a refractive index of 1.70 or more and 1.90 or less, and the mechanical strength of each oxide-sintered body was poor. I knew there was no.

Claims (10)

As an In-Si-O-based oxide sintered body containing In and Si as main components,
Wherein the content of Si is 0.65 or more and 1.75 or less in terms of an Si / In atomic ratio,
The relative density calculated from the actual density of the oxide-sintered body with respect to the density calculated from the existence ratio and the true density of each compound phase constituting the oxide-sintered body is 90%
And a bending strength of 90 N / mm &lt; 2 &gt; or more. The oxide-sintered body according to claim 1, wherein the proportion of the crystalline phase of the silicate indium compound of the tort-buttite structure is 30 mass% or less. The oxide-sintered body according to claim 1, which does not contain a metallic Si phase. The oxide-sintered body according to claim 3, wherein the metal Si phase is not detected by the X-ray diffraction method of the oxide-sintered body powder and / or the electron beam diffraction method of the thin flakes of the oxide-sintered body. The oxide-sintered body according to claim 1, which does not contain a crystalline silicon dioxide compound phase. The oxide-sintered body according to claim 5, wherein the crystalline silicon dioxide phase is not detected by the X-ray diffraction method of the oxide-sintered body powder and / or the electron ray diffraction method of the thin flakes of the oxide-sintered body. The metal element according to claim 1, further comprising at least one metal element selected from the group consisting of trivalent or more metal elements other than In and Si, wherein the content of M when the total content of the metal element is M And an M / In atomic ratio of 0.001 or more to 0.05 or less. A method for producing an oxide-sintered body according to claim 1,
Wherein the amorphous silicon dioxide powder is sintered by an atmospheric pressure sintering method using indium oxide powder as a raw material of In and amorphous silicon dioxide powder as a raw material of Si, respectively. The method for producing an oxide-sintered body according to claim 8, wherein the compact is sintered at a temperature of 1100 ° C or more and 1400 ° C or less. An oxide film obtained by a sputtering method using the oxide-sintered body according to claim 1 as a sputtering target,
Wherein the refractive index is 1.70 or more and 1.90 or less.